问题来源: http://www.cnblogs.com/del/archive/2008/11/14/1120015.html#1370413
StrUtils 单元和 Math 单元 分别有一个 IfThen 函数(注意参数是数字还是字符串),举例:
StrUtils 单元和 Math 单元 分别有一个 IfThen 函数,举例: unit Unit1; interface uses Windows,Messages,SysUtils,Variants,Classes,Graphics,Controls,Forms,Dialogs,StdCtrls; type TForm1 = class(TForm) Button1: TButton; Button2: TButton; procedure Button1Click(Sender: TObject); procedure Button2Click(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} uses StrUtils,Math; procedure TForm1.Button1Click(Sender: TObject); var a: Integer; str: string; begin a := 1; str := StrUtils.IfThen(a > 0,‘aaa‘,‘bbb‘); ShowMessage(str); {aaa} a := -1; str := StrUtils.IfThen(a > 0,‘bbb‘); ShowMessage(str); {bbb} a := 1; str := StrUtils.IfThen(a > 0,‘aaa‘); ShowMessage(str); {aaa} a := -1; str := StrUtils.IfThen(a > 0,‘aaa‘); ShowMessage(str); {} end; procedure TForm1.Button2Click(Sender: TObject); var str: string; num: Integer; begin str := ‘万一‘; num := Math.IfThen(str <> ‘‘,99,11); ShowMessage(IntToStr(num)); {99} str := ‘‘; num := Math.IfThen(str <> ‘‘,11); ShowMessage(IntToStr(num)); {11} str := ‘万一‘; num := Math.IfThen(str <> ‘‘,99); ShowMessage(IntToStr(num)); {99} str := ‘‘; num := Math.IfThen(str <> ‘‘,99); ShowMessage(IntToStr(num)); {0} end; end.